Roman Numbers Converter
Convert between integers and canonical Roman numerals using strict standard subtractive notation.
Standard subtractive notation only: integers 1–3999, or canonical Roman numerals.
A QUICK WALKTHROUGH
How to use this tool
- Choose a conversion direction.
- Enter an integer from 1 to 3999 or a canonical Roman numeral.
- Convert and copy the local result.
Strict standard range
Number input accepts integers 1 through 3999. Roman input must be the unique canonical form for that value; invalid repeats, ordering, and non-standard subtractive combinations are rejected.
Bidirectional local conversion
Both directions run in this browser. No input or result is uploaded or stored.
GOOD TO KNOW
Common questions
Does it support zero or negative numbers?
No. Standard Roman numerals in this tool are limited to integers 1 through 3999.
Are lowercase or non-standard forms accepted?
No. Enter uppercase canonical forms such as IV, IX, XL, XC, CD, or CM.